Falling for the fourth straight session, the 30-share index moved further down by 65.38 points, or 0.32 percent, to 20,660.05. In the past three sessions, Sensex had lost nearly 169 points. The wide-based National Stock Exchange index Nifty traded 26.30 points, or 0.43 percent, lower at 6,138.05.

Brokers said sustained selling by participants at prevailing levels, amid a weakening trend on other Asian bourses, mainly led to fall in stock prices. In the Asian region, Hong Kong's Hang Seng fell by 0.34 percent, while the Japan's Nikkei by 1.20 percent in morning trade on Friday. The US Dow Jones Industrial Average ended 0.62 percent higher on Thursday.